<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>案例4</title>
		<style type="text/css">
			#div1{
				margin-left: 250px;
			}
			#div2 div{
				margin-top: 10px;
				height: 200px;
				width: 200px;
				float: left;
				margin-left: 10px;
				background: #000000;
			}
		</style>
	</head>
	<body>
		<div>
			<div id="div1">
				<button type="button" id="btn1">点击将DIV变成红色</button>
			</div>
			<div id="div2">
				<div></div>
				<div></div>
				<div></div>
			</div>
		</div>
	</body>
</html>
<script src="../js/jquery-3.5.1.min.js" type="text/javascript" charset="utf-8"></script>
<script src="./js/test4.js" type="text/javascript" charset="utf-8"></script>
